Fluid-rock interactions and their implications on carbonate reservoir characterization

The objective of my research has been to define the interactions between fluid and rock properties at different environmental conditions and observation scale to reduce the uncertainty in the carbonate reservoir characterization. Here, I integrate field observations, subsurface data, petrophysical and frictional laboratory measurements focusing on carbonate-bearing rocks to better constrain factors controlling fluid-rock interactions with applications to active petroleum systems. In particular, I focus on the Burano-Bolognano carbonate petroleum system that extends from the northern sector of the Majella mountain to the Cigno/Vallecupa oil fields, in Abruzzo Region (Central Italy). This area is of particular interest because of the following reasons: It has received great attention by oil companies in the past for its structural, stratigraphic, and geodynamic evolution, which led it to be an important target for hydrocarbon exploration during the past century. For this reason, it is characterized by a public dense dataset of wells, reports, maps, etc. It allows to study all petroleum system elements (with the exception of the source rock), such as: reservoir, seal, traps, and migration pathways at field scale. It allows to understand the influence of subsurface fluids on the petrophysical properties of carbonate reservoir rocks since the outcropping portions of reservoir interval are both clean and hydrocarbon-saturated. This allows measuring and comparing the variations of petrophysical properties between hydrocarbon-bearing and hydrocarbon-free samples. It is regarded as an analogue of a faulted and fractured reservoir for other carbonate petroleum systems worldwide and in particular in the Adriatic area. The results of my research quantify the influence of fluid properties in changing of the petrophysical and frictional properties of the bearing-carbonate rocks. The presence of viscous fluids, such as heavy hydrocarbons, at ambient temperature defines an increase of the wave velocities respect to those of the unsaturated samples and determines a possible strengthening and stiffening of the reservoir rock. With increasing temperature, distinct downward trends are recorded, especially for the P-wave velocities. Moreover, the presence of fluids along faults promotes a slow slip behaviour, which was more marked with the presence of clay minerals along fault surface. Finally, starting from these results, I simulate the evolution of the Burano-Bolognano petroleum system and the related fluids movements, inferring that within this petroleum system the vertically hydrocarbon migration is driven by fractures/faults and the subsequently lateral migration determinates a gradual oil biodegradation with an increase of its density.